SSH environment forwarding will propagate this "LC_CTYPE=UTF-8" setting from Mac OS X clients to Linux servers.

At present, that breaks in multiple ways, as CPython will interpret it as being the "C" locale (since Linux servers don't offer a "UTF-8" locale, even when they do offer "C.UTF-8")

PEPs 538 and 540 aim to help CPython itself to deal with that case, but that won't be sufficient to help code that tries to pass the nominal LC_CTYPE setting to the locale module.

Accepting "UTF-8" and interpreting it as functionally equivalent to C.UTF-8 will mean that this setting will at least work as desired on servers that offer C.UTF-8.